Mining process



Sept. l2, 1939. v H. l REED 2,172,683

MINING PROCESS gmc@ H. L.. REED MINING PROCESS Sept. 12, 1939.

3 sheets-sheet 2 Filed Aug. l0, 1937 H. L. REED MINING PROCESS Sept. 12, 1939.

Filed Aug. 10, 1957 3 Sheets-Sheet 3 ,A v LV m. ."n

tmf

Patented Sept. 12, 1939 UNITED STATES MINING PROCESS Howard L. Reed, Houston, Tex., assignor of eleven and one-third per cent to Fohs Oil Company Application August 10, 1937, Serial No. 158,305

4 claims. (c1. 2oz-3) This invention relates to a process of mining and more particularly has reference to the removal of minerals from a considerable distance below the surface of the ground without the diili- 5 culties previously attendant upon mining of such ores.

In the past, minerals have been removed from the ground in a number of ways, chief among which are the removal by simple excavation and L bodily removal, and in some instances, by the circulation of a fluid medium for the purpose of\ bringing the minerals to the surface in the form of solutions. The present invention has reference to the latter general class of mining proc- I esses.

The miningl of minerals by means of circulated fluids has in the past been limited to those minerals which could be melted or taken up by an aqueous displacement medium. The most noted 0 process of removing a mineral by means' of an aqueous medium is the well-known Frasch process, widely utilized in the mining of sulphur. In this process superheated water is forced into the sulphur well to the sulphur-bearing limestone 3,-, beds, and by virtue of the stored heat in the water the sulphur is melted andcaused to flow to the surface of the ground. However, the sulphur occurs in a relatively pure form in nature and is not changed chemically nor dissolved to s0 any substantial degree during the process.

It is an object of this invention to provide a mining process by which minerals may be more cheaply and readily removed from the earth.

It is a further object to provide a process of 15 mining which will enable the ready removal of minerals from hitherto inaccessible ore deposits.

It is an object of this invention to provide a mining process whereby mineral ores are not soluble in or meltable by an aqueous circulating mmedium may be removed from the ground.

It is a further object of this invention to provide a mining process by which mineral ores highly insoluble in a liquid medium in their natural state may be removed from the ground .i through the circulation of a liquid medium.

It is a further object of this invention to provide a mining process by which mineral ores normally extremely diicult to remove by any previously known process may be readily removed u' from the ground.

It is a further object of this invention to proi vide a mining process of the liquid displacement type which Will have a broader application than previously known processes of this general na- :i ture using aqueous displacement media.

. of limitation.

It is a further object of this invention to provide a mining process employing a liquid displacement medium and to provide a liquid displacement medium for such process which will eliminate many of the heat losses and other disadvantages inherent in previously employed circulating media.

It is a further object of this invention to provide a mining process for the removal of ores from the earth through the use of a circulating 1.0 medium which will readily dissociate the various minerals from the gangue and remove them to the surface, and from which the various minerals may be readily extracted.

It is a further object of this invention to provide a circulating medium for use in removing mineral ores which circulating medium is not susceptible to theI temperature limitations of a superheated aqueous medium which has a relatively high vapor pressure, but which may be 2 0 readily vaporized to recover the minerals therefrom.

It is a further object of this invention to provide an improved process of mining, employing a liquid circulating medium and for removing 2:5V

the minerals from the circulatingmedium.

It is a further object to provide a liquid circulating medium for a process of mining, the chemical activity of which will increase with increase in temperature.

It is a further object to provide a liquid circulating medium for a process of mining, which medium will more readily than water or other aqueous medium take into solution the minerals to be removed. f

It is the object of this invention to transform minerals and native metals to substances which may be electrolytically dissociated into sulphur vapor and pure elements, thus producing the constituents by a single continuous automatic 40 process.

It is a further object of this invention to provide a method of mining including the displacement of minerals by a circulating medium which may, itself, be later removed by displacement with a cheaper medium.

One other object is to provideva continuous process of mining and refining the minerals mined.

Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, it being understood that same are by way of illustration only, and not by Way Fig. 1 is a diagrammatic illustration of an apparatus which may be used in the carrying out of a process of mining in accordance with this invention.

Fig. 2 is a verticalcross section of the lower portion of a well illustrating diagrammatically a slightly modied well arrangement for use in connection with this invention.

Fig. 3 illustrates still another form of well arrangement.

Fig. 4 illustrates a fourth form of arrangement of wells for use in connection with this invention.

In practicing. the present invention there is employed a circulating medium consisting for example of molten or superheated sulphur or a medium containing sulphur or having certain of its attributes.

For the removal of minerals from the ground, Fig. 1 illustrates a set-up in which two wells have been drilled to spaced points in the ore. stratum. These wells may be drilled inv any acceptable manner, the details thereof forming no part of this invention. They are designated in Fig. 1 of the drawings by the numerals I and 2, respectively. After the two walls have been drilled, a channel is opened along the mineralized fractures between the wells by some means such as for example the detonations of an explosive charge at the bottom of one or both wells within the producing formation. If detonations are caused in both wells, they may be simultaneous or spaced as to time. These detonations may be repeated of course as many times as may be necessary to open up a channel between the wells.

To the well designated by the numeral 2,

f which may be termed the outlet Well, is connected a pipe 3 leading to the lower end of a gravity separator chamber 4 having a gas outlet 5 at its upper end. Leading from a point intermediate the ends of the separator l in a substantially horizontal direction is a pipe 6 extending over a trap 'I and this pipe and an exhaust pipe 8 leading from the lower end of the separator, are connected to a concentrator chamber 9. Leading from spaced points along the height of the concentrator 9 are lead-off pipes numbered II, I2, I3, I4 and I5, respectively, the highest being numbered I I, and the lowest I5. A vapor conduit I 6 leads from the upper end of the concentrator to the Aintake of the compressor I'I, the outlet I8 of whichfleads to a boiler I9.

'I'he lead-off pipes II to I5 lead respectively to the interiors of a bank of electrolytic cells. Each of these cells has a shell containing a oating anode 2| of carbon or the like, the shell 20 providing the'cathode. 'I'he shell 20 is thus connected by a conductor 22 to the negative pole of a source of electrical energy, and the anode 2l by a conductor 23 to the positive pole of such source. The carbon anode 2| is provided with vertical openings therethrough to increase the Leading ofi' from the upper end of each shell 29 isa vapor pipe 24 which is joined to the line I6 at 25 before the pipe I9 enters the compressor I'I. From the lower end of this shell 29.

extends a drain pipe 26. Leading from the dome of the boiler I9 is a pipe 21 which connects the boiler to the well I which may be termed the input well. that additional pumping facilities may be provided if necessary to maintain circulation. A

f second pipe 28 leads from the boiler dome to the extreme lower end of the concentrator 9 as shown at 28a, and has a branch 2lb which leads to the lower end of a reducing tower 29 having a body or bodies of carbon disposed therein and shown at 28a.

A compressor is connected to the opening 5 at the upper end of the separator 5 and the discharge thereof is connected likewise to the lower end of the reducing tower 29. Adjacent the upper end of the reducing tower 29 is a. pipe 3Ia leading from the reducing tower through` I9 is then forced into one of the wells underl pressure and circulated through the two wells by means of the compressor I1 displacing the previously circulated liquid medium. In passing through the producing stratum between the two wells, the molten sulphur will be brought into intimate contact with the ores containing the mineralsl to be removed.

Thermochemical mining of minerals from their ores consists of altering them by means of a molten displacement medium which will' produce them in suspension or solution when it is circulated through the ore body and vaporized at `the surface in order to obtain the concentrated altered minerals.

In the case of molten sulphur circulated through a body containing cupric oxide in an enclosed system, the oxide is immediately attacked by the sulphur, forming cupric sulphide and sulphur dioxide which are both dissolved by the molten sulphur.

It is also worthy of notethat in the practice of this method whenever the molten sulphur comes in contact with water during circulation through the ore body the water is attacked immediately by the sulphur forming hydrogen It is to be understood sulphide and sulphur dioxide, both of which are appreciably dissolved in the sulphur. -.The hydrogen sulphide thus formed is characteristic of this system of mining because when molten sulphur is forced into a well as in carrying out the present process, the molten sulphur medium will contact water of hydration and crystallization, as well as certain other moisture which may be artificially introduced at the surface. The hydrogen sulphide formed as Just set forth Will at least partially dissolve in the molten sulphur and supply sulphide ions which in turn will be consumed by the chemical alteration of the native minerals to sulphides.

The hydrogen sulphide production either in the above examples or in this mining method is limited by the enclosed system to that which will dissolve in the molten sulphur at the existing replenishment will depend upon the speed at which they are consumed by the alteration of such minerals as native copper to cupric sulphide. The alteration of these minerals will thus be stimulated in some cases by the presence and consumption of the sulphide ions supplied by the dissolved hydrogen sulphide. The alteration of other minerals; such as the metallic oxides, will not/be stimulated by the presence of these sulphide ions, but will be the result of the direct re` placement of oxygen by sulphur, or of some other constituentof the mineral by sulphur.

'Ihe concentration of the dissolved sulphur dioxide will thus depend on the amount of mineral alteration and consequentlywill be large. Since the equilibrium between the hydrogen sulphide and sulphur dioxide formed from water and sulphur must be maintained, excessive quantities of sulphur dioxide will inhibit the formation of hydrogen sulphide unless it is removed from the system. This may be accomplished most readily at the separator 4 where the escape of all gases from the system is permitted, as hereinafter described.v

The minerals foundin the earth are generally classified according to the chemicalactivity of the metals they contain. Those which are comparatively inactive occur generally as free or native metals or as sulphides. Those which are comparatively yactive occur generally in very stable forms such as silicates, titanates, tantalates and fiuorides, and the intermediate group occur ordinarily as oxides, c'arbonates, sulphates and sulphites. l

Of this inactive group, those occurring as sulphides are for the most part soluble in sulphur, while those which occur as native `elements may be divided into two classes. 'I'he rst of these classes consists of those which fall into groups 1B, IIB, IVA and VA of the periodic table, since these have an affinity. for sulphur, and hence will combine with molten sulphur to form sulphides and may then be carried off either in solution or in suspension. This class of native elements is particularly reactive with sulphide ions, as supplied by dissolved hydrogen sulphide. The sec-l ond of these classes, consisting of those falling in the remaining groups of the periodic table, show relatively slight ailinity for molten sulphur and hence willnot to `any substantial degree combine with sulphur and consequently cannot *be removed by this method.

The active or highly oxidized group, such as the silicates, will, in most instances, not react with molten sulphur, but may, in some instances, react with sulphur to form thionates. some of the oxygen atoms will be replaced by sulphur atoms. The solubility of such thionates in sulphur is appreciable.

'I'he intermediate group may be similarly produced by the present medium, in solution and suspension, the oxides being altered -to sulphides by the direct replacement of the oxygen atoms by sulphur atoms and by the consequent formation of sulphur dioxide and the mineral sulphide. The carbonates will ordinarily remain inert and will not'dissolve or be otherwise altered. The sulphates and sulphites are in general effectively That is,v

soluble in lthe molten sulphur, and will thus be produced in solution or suspension.

From the foregoing, it will be noted that strictly speaking the removal of the minerals by means of circulating a sulphurized medium, such as above contemplated, is not a removal by displacement, but is instead a removal by alteration and conduction. That is to say, while the removed ores are of course replaced by the sulphur medium, they are not removed by displacement. Instead, there is the chemical alteration and the subsequent conduction or carrying off of the products of this alteration by the highly heated circulating medium which provides for the removal of the minerals and not simply their vdisplacement by the circulating medium.

When the mineral-laden molten sulphur arrives at the top of the second well, it is then conducted through a series of treatments which may be independent of the nature of the mineral which is-being removed. The sulphuretted mineral as above pointed out will be found in the circulating medium generally in the form of a sulphide either in solution or in suspension, and

, the circulating medium will also be found to conby gravity the light, inert substances suspended in the sulphur, such as the siliceous impurities of the gangue, etc., will be separated. In this device, any steam which may exist, as well as the sulphur dioxide and other gases, will be permitted to escape through the upper end of the separator, and any floatable impurities will be caused to pass off through the line 6 and out through the trap 8. The stream conveying such floating impurities to the trap 1 will pass on and into the concentrator 9. The sulphurized medium still containing the mineral consti-tuentsfrom the ground will be conducted b y means of the line 8 into the bottom of the concentrator 9 wherein the sulphurized medium will be vaporized, and the disseminated sulphides produced by displacement of the activated. minerals will be separated by differential floating in the rising medium within the concentrator or vanorizer 9.

The altered minerals, depending upon whether they are light sulphides or heavy sulphides, will be removed through the lines II, I2, I3, I4 and I5. The sulphur vapor will pass 01T through the vapor line I6 to the intake end of the compressor I I where it will be reliquied and conducted through the line I8 to be injected into the boiler I9. It is noted that the gases passing oi from the upper end of the separator are compressed by the compressor 3l)l and'forced through the reducing tower 29 containing the carbon 29a. 'Ihe concentrator 9 and the reducing tower 29 are to form vcarbon dioxide and free liquid sulphur. t

concentrator 9 where in vapor form itwill be carried on through the line IB to the compressor I1. Any steam discharged from the relief valve 5 will also be discharged from the relief valve 3io, unless altered to sulphur dioxide and hydrogen sulphide in the reducing tower 29, such sulphur dioxide being reduced to liquid sulphur A and carbon dioxide, as above.

. The hot sulphide/s from the concentrator 9, which sulphides pass out through the lines Il, I2, I3, I4 and I5, are conducted to the series of electrolytic cells where they will be dissociated into the liquid metals and boiling sulphur. The sulphur vapor from these electrolytic cells is carried of! through the lines 24 from the tops of the respective cells, which lines join at, 25 the sulphur vapor line I6 so that all the sulphur vapor is conducted to the compressor I1 as previously Vset forth. Each of the cells adjacent its lower portion is provided with a discharge line 26 through which the liquid metals will be discharged from the electrolytic cells.

The heat losses from the concentrator 9 are not necessarily large, even though the sulphur medium is being removed by vaporization at the top of this unit, since the pressure maintained in the concentrator is less than one atmosphere as a result of the suction created by the compressor, thus lowering the vaporization temperature below the normal boiling point of the sulphur. The temperature of the electrolytic cells on the other hand is relatively high in order that the dissociated metals may be continuously removed as liquids from the electrolytic cells wherein they have acted as liquid cathodes. 'Ihe vertical separation of the cathodes from the anodes in these cells may be controlled by the rate at which the metals are removed from the cells. The boiler I9 which provides the superheated sulphur which is used in this circulation process is connected by meansof a line 21 to the well i it may be possible to have the circulation take so that sulphur from the boiler will ypass back again through the well I and into the formation to repeat the cycle.

While it is desirable in many instances where place as above described, employing two wells and circulating the iiuid along a path between the two wells through the producing formation, it is conceivable that a formation might be enl countered of such a nature and in such a locaof the well. The surface casing 36 extends downwardly to the upper end of the cavity and is open at its lower end as indicated at 31. Thus, a hot circulating fluid vpassed downwardly through the tubing would be propelled with considerable velocity through the nozzle-like openings 34 and caused to wash against the walls 35 of the producing formation. The ores contained in the formation would be transformed in the same manner A as in the previously described process, andthe sulphur carrying the minerals would then be passed upwardly through the lower end 31 of the surface casing and up through the casing into the separating apparatus previously referred to.

Another arrangement desirable in instances where the producing formation is at a steep inclination is shown in Fig. 3. In this case, the well 38 is drilled so as to extend into and along the producing stratum. The tubing 39 is then placed in the cased well. and the heated sulphur forced down the tubing and up around the tubing, thus contacting the ore body along a considerable distance as it returns around the tubing. As in Fig. 2, the tubing may be raised or lowered as the formation becomes exhausted,

in separating the minerals from the circulating medium.

It will be appreciated from the foregoing that there may be many immaterial variations of the process set forth without departing from the spirit or scope of this invention.

It is intended that the scope of this invention shall cover all such variations as may fall within the terms of the appended claims.

Having described my invention, I claim:

l. In a method of mining, the steps of circulating Ymolten sulphur through an ore deposit, and treating the molten sulphur as it comes from saidcre deposit to remove therefrom minerals taken up by the molten sulphur from the ore deposit.`

2. In a method of mining, the steps of circulating a molten sulphur through an ore deposit, permitting the gas contained in said molten sulphur to escape therefrom as it comes from the ore deposit, vaporizing a portion of said molten sulphur, and performing electrolysis on the remainder of said molten sulphur to separate therefrom the mineral constituents taken up from said ore deposit.

3. In a method of mining, the steps of circu lating ay molten sulphur through an ore deposit, permitting the gas contained in said molten sulphur to escape therefrom as it comes from the ore deposit, vaporizing a portion of said molten sulphur, performing electrolysis on the remainder of said molten sulphuixtoV separate therefrom the minerals taken up from said ore deposit,l recovering sulphur from the gases given oif by said molten sulphur, and re-liquifying the vaporizing sulphur, reheating the total recovered sulphur and re-circulating the same.

4. In a method of mining, the steps of circulating sulphur through an ore deposit, and treating the sulphur as it comes from said ore deposit to remove therefrom minerals taken up by the sulphur from the ore deposit.

HOWARD L. REED. 

